The present invention pertains to the field of computers. More particularly, the present invention relates to accessing resources not mapped to a subsystem in a computer based system without involvement of the main operating system.
Computer based systems are becoming more mobile. This mobility often places an emphasis on usability. Usability is often extended by the ability to operate the equipment for longer periods of time. This time period is often related to the power consumption of the equipment, particularly in battery operated equipment. Thus, high power consumption may pose problems.
Numerous approaches to reducing power consumption have been tried. Powering off equipment when not in active use is one approach. Other approaches involve putting equipment in various lower power states, such as, idle mode, sleep mode, hibernation mode, etc. Such approaches may involve turning off portions of circuits or components, powering down subsystems and/or the main system, lowering supply voltages, altering clocking mechanisms, transferring data from, for example, random access memory (RAM) to disk storage, etc.
One such approach to conserve power consumption is to have the host or main central processing unit (CPU) powered down while having a subsystem active. The subsystem may need to transfer information for which the host CPU upon exiting a powered down state boots up the operating system, performs the transfer, and then powers down. Time required to boot up the operating system may present a problem for a subsystem that needs a rapid response. Power consumed during the boot up process may also present a problem for battery operated equipment.